Such cutting tools include, for example, reamers, drills and end mills, typically for machining metals. Typically the tools are held in tool holders for fixing to a rotatable drive spindle of a machine tool Precise working of a workpiece by rotating cutting tools requires precise alignment of the tool axis with the axis of rotation of the spindle. Radial runout of the cutting tool may be due, for example, to axial displacement of the tool axis relative to the axis of rotation or due to spindle or tool axis angle errors relative to the axis of rotation of the spindle. Radial runout causes the cutting tool to rotate eccentrically, which leads to a corresponding loss of accuracy in the workpiece being machined.
Prior art that has addressed the problem of correcting radial runout includes, for example, GB 2356828; U.S. Pat. Nos. 4,776,734; 7,165,923; 7,037,053. Prior art cutting tools with runout correction suffer from a number of disadvantages. Just to mention a few, some are structurally complex. Some require dedicated runout correction devices that cannot be applied to existing cutting tools that do not have runout correction ability. Some only enable runout correction for a finite set of discrete radial directions. In some of the prior art cutting tools, a screw is used to apply a deflecting force. The screw has a frusto-conical bearing surface that applies a bending force directly to the cutting tool as it is being tightened. Consequently, the bearing surface will become worn due to friction as it rotates and simultaneously applies a bearing force to the cutting tool.